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我有一个 Django 模型，它不包含“id”字段，但在我之前迁移的 MySQL 实例中，由于某种原因，它显示了一个“id”字段。我不断收到错误消息：

You are trying to add a non-nullable field 'id' to discussions without a default; we can't do that (the database n
eeds something to populate existing rows).

所以我去检查了models.py没有“id”字段的文件：

class Discussions(models.Model):

    #team_id = models.ForeignKey(Teams, null=True, on_delete=models.CASCADE)
    login = models.CharField(max_length=30, null=True)
    uid = models.PositiveIntegerField(primary_key=True)
    title = models.CharField(max_length=30, null=True)
    body = models.CharField(max_length=500, null=True)
    comments = models.CharField(max_length=30, null=True)
    updated_at = models.CharField(max_length=21, null=True)

但它出现在我的 MySQLdescribe语句中：

+------------+--------------+------+-----+---------+----------------+
| Field      | Type         | Null | Key | Default | Extra          |
+------------+--------------+------+-----+---------+----------------+
| id         | int(11)      | NO   | PRI | NULL    | auto_increment |
| login      | varchar(30)  | YES  |     | NULL    |                |
| comments   | varchar(30)  | YES  |     | NULL    |                |
| updated_at | varchar(21)  | YES  |     | NULL    |                |
| body       | varchar(500) | YES  |     | NULL    |                |
| title      | varchar(30)  | YES  |     | NULL    |                |
+------------+--------------+------+-----+---------+----------------+

当我删除表以尝试重新同步数据库时，我收到一条错误消息：

django.db.utils.ProgrammingError: (1146, "Table 'my_project.app_discussions' doesn't exist")

理想情况下，我希望有某种方法可以让我的uid变量在我的视图中实际加载到我的数据库实例中，其中id表示该字段。

        # tree->tuples->list of tuples
        json_tree = objectpath.Tree(data)
        login = tuple(json_tree.execute("$..login"))
        uid = tuple(json_tree.execute("$..id"))
        title = tuple(json_tree.execute("$..title"))
        body = tuple(json_tree.execute("$..body"))
        comments = tuple(json_tree.execute("$..comments_count"))
        updated_at = tuple(json_tree.execute("$..updated_at"))

        # took out `uid`
        parsed_list = list(zip(login, uid, title, body, comments, updated_at))

        # LOADING PHASE
        load_data = []

        # took out `u`
        for l, t, i, b, c, u in zip(login, uid, title, body, comments, updated_at):

            load_data.append(Discussions(l, t, i, b, c, u))

        Discussions.objects.bulk_create(load_data)

为什么我无法将这个新模式迁移到 MySQL？为什么这个uid字段在我之前没有通过 ORM 映射到 ID 字段？谢谢你的帮助。

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1 回答 1

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是主id键，它不能为空。因为，您id在以前的迁移中添加了可为空的字段，然后您需要更改以前的迁移或只是在模型中添加新字段并再次运行迁移

id = models.IntegerField(null=False, primary_key=True)
于 2019-05-12T06:24:28.380 回答